Meeting Abstract

The Gene Regulatory Network approach to Evo-Devo promises the discovery of mechanisms of evolutionary innovation as well as of deeply conserved “cassettes” governing fundamental developmental processes. However, defining regulatory interactions on a network scale remains a formidable challenge. We present data from the sea urchin network controlling pattern formation to illustrate two points concerning (1) network methodology in the era of high-throughput genomics and (2) the utility of developmental networks for gaining insight into evolutionary change. First, lessons learned from earlier network studies suggest how next-generation technologies might best be employed to capture critical developmental mechanisms leading to specific and testable hypotheses, or in other words, to produce meaningful networks with real predictive value. Thus, high-throughput does not necessarily have to mean low-resolution. Falling costs, meanwhile, put these goals closer in reach. Second, our data on network dynamics in a euechinoid sea urchin, Strongylocentrotus purpuratus, provide the basis for comparison with development in a cidaroid sea urchin, Eucidaris tribuloides, and a sea star, Patiria miniata. A general finding is that network interactions produce strikingly reliable, robust developmental mechanisms. Next, we identify specific network connections that arose in the euechinoid lineage. Crucially, these appear to have been layered on top of the pre-existing network while leaving ancestral functions intact, thus illustrating the evolutionary principle of accretion as opposed to wholescale replacement. We examine how the result is a complex, multi-layered network, with superficially redundant elements and a highly robust structure.